Polycarbonates are well-known commercially available resinous materials having a variety of applications. They are typically prepared by the reaction of dihydroxy compounds with a carbonate precursor, such as phosgene, in the presence of a catalyst. Methods of direct phosgenation, interfacial condensation and transesterification, for the preparation of polycarbonates, are described in detail in "The Chemistry and Physics of Polycarbonates", by H. Schnell, John Wiley & Co., N.Y., 1964.
Polycarbonates are high temperature, high performance engineering thermoplastics having a combination of good thermal and mechanical properties, especially when prepared from one or more aromatic diols. The blending with polycarbonates of additional compounds, such as for example, other thermoplastic resins, copolymer rubber compounds, and the like, is commonly practiced in order to improve one or more properties of the homopolymer polycarbonate.
The applications for polycarbonates as engineering materials are limited because they generally exhibit severe environmental stress failure. By environmental stress failure is meant surface crazing or cracking, or disintegration of the molded piece resulting from its contact with organic solvents while under stress, such as may occur for example when solvents are used to clean or degrease stressed parts fabricated from polycarbonates or polycarbonate blends.
U.S. Pat. No. 3,431,224 discloses a blend of a polycarbonate and a polyolefin such as polyethylene or an olefin copolymer such as ethylene/propylene, in order to improve the environmental stress failure resistance of the homopolycarbonate. U.S. Pat. No. 3,780,140 discloses a terpolymer of ethylene, carbon monoxide and a third component such as vinyl acetate, for blending with a polycarbonate to improve impact resistance.
U.S. Pat. No. 3,248,359 discloses the use of an ethylene/carbon monoxide copolymer for improving the environmental stress failure resistance of polyolefins such as polyethylene. Finally, U.S. Pat. No. 2,541,987 discloses a copolymer of ethylene and carbon monoxide as a plasticizer in chlorinated vinyl polymers such as polyvinyl chloride. The prior art does not suggest that an ethylene/carbon monoxide copolymer would be an effective blend component for increasing the environmental stress failure resistance and impact resistance of polycarbonates.